TIME-GATED PHOTON-ECHO SPECTROSCOPY IN LIQUIDS

Optical dephasing of a cyanine dye chromophore in solution is investig ated by time-gated photon echo spectroscopy in a three-pulse scatterin g geometry. The third-order polarization response is gated by up-conve rsion with a reference pulse in a nonlinear optical crystal. Time gati ng establishes two controllable periods of system evolution in an opti cal coherence. The measurements are compared with numerical simulation s employing the measured OKE spectrum of solvent (butanol, DMSO) fluct uations. The time-shift of the time-gated echo signals for several gra ting forming pulse time delays agrees with simulation while the narrow er simulated widths suggest a frequency-dependent solute-solvent inter action and the consideration of chromophore vibronic transitions.